Pyrithione salts, such as zinc pyrithione, are known to provide excellent biocidal activity, including broad spectrum anti-bacterial and anti-fungal activity. There are many uses for these pyrithiones. By way of illustration, U.S. Pat. No. 4,818,436 discloses the use of pyrithiones in metal working fluids; U.S. Pat. No. 4,401,770 discloses urethane shoe inserts having antimicrobial activity; and U.S. Pat. No. 4,935,061 discloses their use in paints.
Unfortunately, these pyrithiones are solids, and the use of solids, such as powders, in the formulating and processing of polyurethane foams is undesireable for enviromental and safety reasons since the handling of a powder is generally a dusty process. Moreover, a powder is difficult to evenly disperse in a liquid polyol and is subject to settling problems, thus requiring stirring immediately before fabricating a urethane using the solids-containing polyol. Further, the pyrithione solids are difficult to solubilize, and interactions between prospective solvents and the polyols themselves are a particular concern.
Efforts have been made in the past to solubilize pyrithione salts for use in shampoos. For example, U.S. Pat. No. 3,636,213 discloses heavy metal pyrithione salts dissolved in an amine, preferably selected from the group consisting of dodecyl amine and diglycol amine, for use in hair dressings. As another illustration, U.S. Pat. No. 4,835,149 discloses the use of amines, including ethanolamine, diethanolamine, monoisopropylamine and others, together with a cosmetically effective amount of a polycarboxylic acid in the preparation of a shampoo effective for the treatment of seborrhea.
Heretofore, a solution to the problem of solubilizing pyrithione in a polyurethane forming formulation has not been known, to the knowledge of the present inventors. Such a solution would be highly desired by the polyurethanes manufacturing community.